It is known to contact molten cast iron in the casting mold with various treating agents in order to influence the basic structure or the shape of the graphite.
Such treatments rely on the fact that the treatment will be the more effective the shorter is the time between the addition of the treating agent and the solidification of the molten material (German patent publication No. 12 48 239; German Pat. No. 1,172,806).
German patent publication No. 25 18 367 discloses another process, which serves to make modular iron and in which a casting mold provided with an intermediate chamber is used. In that process it is essential that the surface of the graphite-spheroidizing agent contained in the intermediate chamber has always the same area. For this reason it is believed that the base area of the intermediate chamber used in said process is a decisive feature and that other dimensions of the chamber are not significant.
The use of the known reaction chamber has given satisfactory results and permits a favorable utilization of the treating agent. But that process too does not comply in all cases with the conditions encountered in foundry practice.